Saw both of the GTX 1 at the car show last weekend in Palm Springs.
Unfortunately I arrived late in the day and only had a second to say Hi to Kent before he had to leave. Also met another new GT owner who came over from Hawaii and just moved to Palm Springs.
All the pics of the tops that I have seen don't seem to include a rear window which makes it impossible to wash the car or drive it inclement weather. Once more, have the tops been tested at high speeds. I remember when the tops for the Viper came out and they would fly off and speeds over 100mph. With the cost of this conversion, I do hope they test the tops at high speeds and that it comes with a rear window so it can be driven in all weather conditions.
Here is a link that has pictures of the rear window. I would think that conditions warranting the use of the roof would prohibit driving at 100mph+ ie. rain and storms. We certainly don't condone driving those speeds off track, however, should you choose to the roof will handle it just fine.